iChat AV: AVOIDING LATE-NIGHT AUDIO CHATS

If you're working late at night and your spouse and kids are in bed, you may not want one of your buddies calling you for an audio chat. If that's the case, go under the Audio menu and turn off Microphone Enabled. Now, when they look at you in their Buddy List, the green Audio Chat icon will be hidden, and if they want to talk to you, they'll have to text chat.